Work done by a Net Force A NET FORCE causes___________

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Presentation transcript:

Work done by a Net Force A NET FORCE causes___________ *If a NET FORCE does Work, the __________ energy of the object being worked on will change

Work done by a Net Force A NET FORCE causes ACCELERATION *If a NET FORCE does Work, the kinetic energy of the object being worked on will change. So, the Wnet = D KE *A net force does NO work in uniform circular motion. Why?

Final Speed vs Net Work done What is the mathematical relationship between the final speed of an object and the total amount of work (net work) done on it (if it started from rest)?

Wnet = DK W = (F)(Dr) cosq Fnet = ma DK = Kf – Ki K = ½ mv2

Examples & Assignments 1. How much more work must be done (by a net force) to accelerate a 2700kg SUV to 26.8m/s (60 mph) than it takes to accelerate a 1050kg compact car to the same speed? 2. What size net force does it take to stop each car in 50.0m? Assignment: WS on Work and kinetic energy